Coffee kettle

ABSTRACT

A coffee kettle of this invention comprises a filter case (8, 80), a water tank (7, 79) having a heater (6, 78), power supply and control means for supplying power to the heater (6, 78), a steam sensing element (52, 128) to operate upon sensing steam generated from water heated to boiling in the water tank (7, 79), wherein hot water in the water tank (7, 79) is supplied to the filter case (8, 80) by operating the hot water supply valve (38, 100) in association with the movement of the steam sensing element (52, 128).

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to a coffee kettle capable of automaticextraction of tasty coffee liquid by dripping boiling hot water ontocoffee powder.

2. Description of the Prior Art

Among conventional methods of obtaining coffee liquid by dripping hotwater onto coffee powder, are a so-called drip type wherein water isintroduced from the bottom part of a water tank to a heated pipe,heated, and raised by the use of steam generated by nucleated boiling,and dripped onto coffee powder for 10 minutes or so, and a drop-supplytype wherein an water tank is provided with a heater and atemperature-release valve and hot water is dripped onto coffee powderplaced below the water tank.

However, these methods have by such drawbacks that the temperature ofthe supplied hot water is low in an early stage because of theintroduction of cold water mixed therein, a temperature characteristicwhich is below 86° C. even at the point of time of the end of supplyuntil when water has gradually become hotter than before, difficulty inelimination of fluctuation in temperature sensing accuracy, and, as theresult, a temperature of the supplied hot water is indefinite and low,and these methods do not supply boiling hot water of a high temperature.Therefore, these methods cannot satisfy such requirement as "To dripboiling hot water onto coffee powder and, sufficiently swelling coffeepowder, complete extraction within 3 to 4 minutes" which is a key toextraction of tasty coffee liquid.

And, in order to obtain tasty coffee liquid full of flavor and richtaste, known is the utilization of a so-called steaming effect, whereinin the process of coffee essence extraction coffee powder is put into astate that makes easy the extraction of coffee essence by providing alength of time for sufficiently swelling the whole coffee powder withhot water of high temperature and then by supplying hot water once moreonto the coffee powder to efficiently extract coffee essence; but amatter satisfying requirements for extraction at the above-mentionedhigh temperature including such constitution has not yet been realized,thereby genuinely flavorful and rich coffee liquid having beenunobtainable.

SUMMARY OF THE INVENTION

A coffee kettle according to this invention comprises a filter case forcontaining coffee powder, a water tank provided with a heater, anelectric power supply and control unit for supplying electric power tothe heater, a steam sensing element to operate upon sensing steamgenerated when water in the water tank is heated to boiling, and a hotwater supply valve for supplying hot water in the water tank to thefilter case by an action of the steam sensing element, and accordingly,since hot water to be supplied on the coffee powder is necessarilycaused to become boiling water by the action of the steam sensingelement, thereby to make the temperature at which the water contacts thecoffee to be high from the first and to cause the length of time forextraction to become complete time within 3 to 4 minutes, andfurthermore the whole of the coffee powder is swollen at once by hotwater of high temperature so that a steaming effect to make extractionof coffee essence easily becomes expectable.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a sectional view of a coffee kettle showing one embodiment ofthis invention,

FIG. 2 is a partial front view of a main part thereof,

FIG. 3 is an electric circuit diagram therefor,

FIG. 4 is a sectional view of a coffee kettle showing another embodimentof this invention,

FIG. 5 is an enlarged partial view of a main part thereof,

FIG. 6 is a diagram showing the relation between the temperature curveof the steam sensing element and states of a power supply switch and ahot water supply valve,

FIG. 7 is an electric circuit diagram for the second embodiment,

FIG. 8 is an enlarged partial view of a main part of a coffee kettle ofa still another embodiment of this invention, and,

FIG. 9 and FIG. 10 are electric circuit diagrams therefor.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

With reference to the appended drawings, an embodiment of this inventionwill be described as follows:

In FIG. 1 and FIG. 2, numeral 1 designates the body of a kettle which iscomposed of a base 2 shaped like a flat cylindrical vessel, a vesselunit 3 positioned above and facing to the base 2, and a pillar 4 toconnect the vessel unit 3 to the side of the base 2, the body 1 defininga cup receiving space 5 which is open at the left side and looking likea 90°-turned U letter.

The vessel unit 3 comprises, in the upper position a cylindrical watertank 7 made of stainless steel and having a heater 6 for heating waterfixed to the bottom thereof and in the lower position a vessel frame 11having a recessed fitting surface 9 into which a filter case 8 isdetachably fitted from the side of a cup receiving space 5 lying andinternally having hot water supply means 10 for introducing water in thewater tank 7 to the area above the filter case 8 and electricalcomponent parts and so on. The filter case 8 is provided with an upperprojecting surface 12 so as to be fitted into the above-said recessedsurface 9 through a bayonet joint or sliding rails, an extraction port13 at the bottom, and a handle 14 at the top of the side thereof, andalso contains a paper filter 15 into which coffee powder is put. Numeral16 designates a glass cup which is positioned below the filter case 8and has its underside removably placed on the cup receiving part 17 onthe upper surface of the base 2, and the glass cup 16 is provided with alid 19 covering its upper open part and having a liquid receiving port18 facing the extraction port 13 of the filter case and with a handle 22to be fixed to an annular recessed surface 20 of the cup 16 by means ofa fixing piece 21 by utilizing elasticity of resin material or the like.

Numeral 23 designates a cup warming heater provided in the base 2 of thecup receiving part 17. Numeral 24 designates a thermostat fortemperature control over the cup warming heater, and numeral 25designates a magnet plug receiving peg frame provided on the lower partof the pillar 4.

Numeral 27 designates a lid detachably fixed to the upper water supplyport 28 of the water tank 7 by projection-recess engagement with thetank, and integrally composed of an upper knob part 29 made of resin anda lower covering lid 30 made of stainless steel.

The above-mentioned hot water supply means 10 comprises a hot watersupply port 31 on the bottom of the water tank 7, a valve case 33 fixedto this hot water supply port 31 through a waterproof packing 32 in suchmanner that a part thereof protrudes into the water tank 7, a hot watersupply pipe 34 for introducing hot water in the valve case 33 toward theupper part of the filter case 8, and a detachable diffuser 35 made ofstainless steel for evenly dispersing hot water onto coffee powder.

Numeral 36 designates a valve spring for energizing from the upper sidea hot water supply valve 38 fixed to a vertically movable valve spindle37 for adapting the hot water supply valve 38 to close an opening allthe time, and 39 designates a diaphragm for retaining the lower part ofthe valve spindle 37 at the center thereof and to be fixed to a valvecase cover 40 at the periphery, the diaphragm 39 being made of siliconrubber, vertically movable, and water-tightly retained at the fixingpart thereof.

Numeral 41 designates a valve lever which is fixed to a pair ofsupporting pieces 42 protrudingly provided from the valve case 33 andturns around its fixed part 43 as a fulcrum, the left end of the lever41 is adapted to abut on the bottom end of the valve spindle 7 and theright end being provided with a projection 45 for changing over anormal-off contact 44 as a switching element for supplying power to theheater 6 and with a catching part 48 in contact with a catching lever47.

Numeral 49 designates a steam sensing cylindrical tube of stainlessdisposed in parallel with the water tank 7 and protruding above thepillar 4, and the steam sensing cylindrical tube 49 has a verticallysliding rod 50 and a steam sensing element 52 which is located in theupper interior of the tube and between the upper surface of this tube 49and the flange 51 of the sliding rod 50, composed of acoiled-spring-like shape-memory alloy made of Ti-Ni alloy or Cu-Zn alloytreated so as to elongate for restoring to the initial state which thealloy has memorized at a temperature below 100° C. The steam sensingtube 49 positioned outside the steam sensing element 52 is provided withsteam ports 53 by which the inner space of the tube is adapted tocommunicate with the outer space, and, opposite to one of these ports 53an opening 55 of a steam pipe 54 having one end caulked (i.e.squeeze-formed, e.g. crimped) to a part of the water tank higher thanthe specified level of water in the water tank 7 and also having itsmid-portion raised higher than the upper surface of the water tank 7 isdisposed. The steam sensing tube 49 is provided with a peripheral partat the lower end and positionally fixed by a vertically movablewater-tight packing 56 supporting the sliding rod 50 within the tube soas to be water-tightly separated from the pillar 4. However, only anacting part 57 of the sliding rod 50 which downwardly extends beyond andlower than the water-tight packing 56 is adapted to face the uppersurface of the catching part 48 of the valve lever 41 in the pillar 4.

Numerals 58 and 59 designate a push-button power switch providedprotruding from the upper surface of the pillar 4 and anotherpush-button turn-off switch for releasing the suspension of operationprogress, respectively, the former having a lower end formed into twoparts such as a catching piece 62 for catching a switch lever 61energized by a spring 60 and a projecting part 64 for closing a powersource line switch 63 lying below when the catching piece catches theswitch lever, and being so arranged as to return upward by the springforce when released from the operator's hand.

The push-button 59 is also an automatic return type operation switchenergized normally upward by a spring (not shown) and provided with, atthe lower end, releasing pieces 65 and 66 lying near the switch lever 61and a catching lever 47 for operating the above-said valve so as torelease catching engagement of the switch lever 61 and of the catchinglever 47.

FIG. 3 shows an electric circuit diagram, wherein numerals 71 and 72designate power source terminals connected to a power source, forexample, 100 V, and corresponding to a magnet plug 26 shown in FIG. 1.The numeral 63 designates a power source switch to which a seriescircuit including a warming heater 23 and a temperature controlthermostat 24 and another series circuit including the heater 6 forboiling water connected to a normal-off contact 44 as a switch elementand to a safety thermostat (indicated as 67 in FIG. 1) for preventingburning of empty tank are connected to the power source terminal 72through common connection points 69 and 70.

The action of the above-said structure will be described. First, thefilter case 8 containing coffee powder and the paper filter 15 is fixedto the recessed fitting surface 9 and, on the other hand, the water tank7 is fed with a predetermined quantity of water (usually water for aboutfour servings) and covered with the lid 27. When the cup 16 is placed onthe cup receiving part 17 in the receiving space 5, the liquid receivingport 18 of the lid 19 for the extraction port 13 of the filter case 8cup faces. With the magnet plug 26 connected to the peg frame 25 of thebase 2 and the push-button power switch 58 depressed, the power sourceline switch 63 is closed, thereby the cup warming heater 23 and theheater 6 for boiling water being electrified.

And, water in the water tank 7 is heated by the heater 6 to raisetemperature to such an extent to emit faint steam from the surfacethereof at a temperature near 100° C., and, when heated to the boilingpoint of 100° C., it becomes forceful steam, and that it is emittedincessantly. Steam emitting at the boiling point is as forceful asflushing from small slits on the water tank 7. Such forceful steam, as amatter of course, spouts from the opening 55 after passing through asteam pipe 54 provided on the upper part of the water tank 7 and,further, instantaneously spouts onto the coiled-spring-like steamsensing element 52 made of the shape memory alloy through the steamports 53 provided for the steam sensing tube 49.

Then, the steam sensing element 52 is subjected to an abrupt temperaturerise as changing from an ambient temperature of about 30° C. to 100° C.,whereby the coiled-spring-like element that has memorized the shapethereof at a temperature lower than 100° C., for example, 80° C. or so,quickly elongates due to a strong restitutive force thereof.

The movement of the steam sensing element 52 depresses the sliding rod50 and the acting part 57 at the lower end of the rod pushes the uppersurface of the catching part 48 of the valve lever 41, when the actingforce in opposition to the energizing force of the valve spring 36 andanother spring 46 adapts the catching part 48 to turn for catching andlocking the hook of the catching lever 47. At this time, the projection45 of the valve lever 41 depresses and opens a movable piece ofnormal-off contact 44 as a switch for supplying power to the heater 6 soas to stop electrification of the heater 6 and prevent further heatingof water. Also, in the above movement, the left end of the valve lever41 pushes upward the valve spindle 37 via vertically movable diaphragm39, thereby opening the hot water supply valve 38.

When the hot water supply valve 38 is opened, hot water in the watertank 7 is, after passing through an opening 68, valve case 33, and hotwater supply pipe 34, evenly poured onto coffee powder being diffusedfrom perforations of the diffuser 35. Then, the hot water efficientlyextracts coffee essence, is filtered by the paper filter 15 to turn intoclear coffee liquid, and then is contained in the cup 16 after passingthrough the extraction port 13 on the bottom of the filter case 8 andthe liquid receiving port 18 of the cup lid 19 lying below and oppositeto the filter case bottom. On the other hand, coffee liquid in the cup16 is kept warm at an appropriate temperature by the cup warming heater23 controlled by the thermostat 24.

Depressing of the push-button turn-off switch 59 after the use of coffeekettle operates releasing pieces 65 and 66 in such a way to release theswitch lever 61 and the catching lever 47 from catching engagement withrespective partner parts in opposition to springs 60 and 46 of theswitch lever 61 and the catching lever 47, respectively, whereby thepush-button power switch 58 and the push-button turn-off button 59automatically return upward to initial positions thereof by the springforce and the normal-off contacts 44 closes the circuit that has been inthe open state. At the same time, the power source line switch 63 isturned off and electrification of the heater 6 and the warming heater 23is suspended to disconnect the circuit.

In response to the return of the push-button turn-off switch 59, theforce of the valve spring 36 acts upon the steam sensing element 52 viathe valve spindle 37, valve lever 41, and sliding rod 50, when, however,steam has stopped spouting and the shape memory effect has passed away.Therefore, the steam sensing element 52 is easily returned from theshape of the elongated coiled spring to the initial contracted state toclose the hot water supply valve 38, thereby dripping of water does nottakes place even when water is poured into the water tank again.Further, the push-button turn-off button 59 possesses a so-calledreleasing function capable of suspending or releasing the performance,such that, when in midway of heating and supplying of hot water suchactions are desired to be suspended halfway through the operation, byoperating it the catching and locking performance that has put the powersource line switch 63 and the hot water supply valve 38 into open statecan be released.

For the purpose of assuring exact performance of releasing as above, inan embodiment of this invention, the shape memorizing temperature aswell as the shape and the number of steam ports 53 outside the steamsensing element 52 provided in the steam sensing tube 49 are designed tobe effective so that the shape memory effect of the steam sensingelement 52 may rapidly pass away, particularly, at the time of hot watersupply immediately after a steam sensing.

A length of time between pouring of hot water from the water tank 7 ontocoffee powder and extraction of coffee essence is set at about 3 to 4minutes responding to the diameter of the hot water supply pipe 34 andthe length of displacement of the hot water supply valve 38. Therefore,hot water is poured onto coffee powder after once boiled and releasedfrom heating, and thereby it is as hot as 96° C. in temperature at thebeginning of pouring even though losing heat during passing through thehot water supply passage and the like, and, though the temperaturegradually is lowered, it is kept at 90° C. or above ideally forextraction even at the time of completion of extraction.

In this way, an embodiment of this invention is of such structure thathot water is supplied for coffee essence extraction in association withthe movement of the shape memory alloy as a steam sensing element 52which operates upon sensing steam generated from heating to the boilingpoint of water contained in the water tank 7, and therefore, capable ofalmost satisfying such conditions as "To drip boiling hot water ontocoffee powder and complete extraction of coffee within a period of 3 to4 minutes" which is a key to extract tasty coffee liquid, and enablingefficient extraction of coffee essence under ideal conditions forproviding genuinely flavorful and rich coffee liquid.

Since supply of hot water for extraction is started after sensingboiling of water, the water temperature for extraction is free fromfluctuation depending on number of cups for serving, enabling drinkinginvariably and stably tasty coffee liquid at any time desired, and, inaddition, fluctuation in power consumption and in additional voltage inthe heater 6, time lag in temperature sensing between the sensing partand switch part as observed in the conventional device employing athermostat as a water temperature sensing member, and fluctuation insensing in accordance with the setting position of the part are allcompletely eliminated, thereby enabling to possess a high levelreliability and hence markedly improved its commercial value. When theshape memory alloy as a steam sensing element 52 as in this embodimentis adopted, two functions as steam sensing and mechanical operation canbe possessed simultaneously, and, as a result, not only the structure issimplified but also time lag in operation is eliminated, and it becomessmall in size, light in weight, and low in price. Besides, use in thesteam sensing being the performance of sensing of quick change betweenthe normal temperature of water to the boiling point, it is possible toallow a setting of a shape memory temperature to have a range andeliminate sensing error caused by fluctuant temperature, and therebyhigh reliability and reduced production cost become further possible.

As in an embodiment of this invention, when steam sensing is performedoutside the water tank 7, even for such a structure as employing a watertank 7 made of stainless steel wherein sufficient confirmation of coffeeextraction process is impossible, such evaluation of the commercialproduct that a process of coffee extraction can be enjoyed by visualconfirmation of a state as steam spouting. Therefore, employment of astainless steel water tank 7 enables the use of hot water of nearly 100°C., contrary to the conventional plastic tank limited to the use of coldwater only, and makes easy handling, and eliminates unfavorableinfluence as smell of plastics upon extraction of coffee essence.

Since the configuration is such that diselectrification is made byopening the switch element 44 closing the circuit of the heater 6 inassociation with the movement of the steam sensing element 52,prevention of burning of the water tank 7 after the end of hot watersupply becomes possible, and such action can be made automatically,leading to excellent safety and operability.

As regards the above embodiment, a description has been made on thestructure in which the steam sensing element 52 made of the shape memoryalloy is shaped like a coiled-spring and disposed upright outside thewater tank 7; however, it is a matter of course that configuration isnot limited to the above-mentioned one and may be appropriately modifiedto be embodied without departing from the scope of the concept, forexample, a sensing element shaped straight, and disposed in the watertank may be possible.

In the above embodiment, although the valve lever 41 is brought intocatching engagement with the catching lever 47 for enabling continuouslocking, such catching engagement may be adapted to continue for apredetermined time (e.g. 3 to 4 minutes before completion of hot watersupplying) and be provided with a time limiting element for releasingthe engagement and restoring the initial conditions.

Further, in the above-mentioned embodiment, the description was made onthe method of releasing the operation by means of the push-buttonturn-off switch 59, however, a structure capable of opening the valve inassociation with the application of the lid 27 or the filter case 8 tothe kettle may suffice.

Now, another embodiment shown in FIGS. 4 through 7 will be described. Inthese drawings, numeral 73 designates a body of a kettle composed of abase 74, a vessel unit 75 positioned above the base 74, and a pillar 76connecting the vessel unit 75 with the side of the base 74. A receivingspace 77 is provided on the left side of the pillar 74 on the drawing.The vessel unit 75 is composed of a water tank 79 made of stainlesssteel and having a heater 78 fixed to the bottom thereof, a recessedfitting surface 81 into which a filter case 80 is detachably fitted, anda vessel frame 83 internally containing hot water supply means 82 forupwardly guiding water in the water tank 79 toward the area above thefilter case 80 and other electrical wiring parts. The filter case 80 isprovided with an upper projecting surface 84 to be fitted into theabove-said recessed surface 81 through the bayonet joint or slidingrails, an extraction port 85 at the bottom and a handle 86, and alsocontains a paper filter 87 into which coffee powder is put. Numeral 88designates a cup which is positioned below the filter case 80 andremovably placed on the cup receiving part 89 above the base 74 and isprovided with a cup lid 91 having a liquid receiving port 90 facing theextraction port 85 of the filter case 80 and a handle 92 for holding.

Numeral 93 designates a warming heater for cup warming provided in thebase 74 of the cup receiving part 89, numeral 94 designates a thermostatfor temperature control and numeral 95 designates a lid of the watertank fixed on the upper water supply port 96 of the water tank 79. Theabove-mentioned hot water supply means 82 comprises a hot water supplyport 97 provided on the bottom of the water tank 79, a valve case 99fixed to this hot water supply port 97 through a water proof packing 98in such manner that a part thereof protrudes into the water tank 79, ahot water supply pipe 101 for upwardly introducing hot water from thevalve case 99 to the area above the filter case 80 through a hot watersupply valve 100 and a diffuser having a function to evenly dispersinghot water onto coffee powder.

In the valve case 99, further provided are a valve spring 103 acting toclose the hot water supply valve 100 all the time in an upper position,and in a lower position a diaphragm 105 made of a silicone resin andfixed to the valve case 99 at the periphery by means of a valve casecover 104 and shaped to be vertically movable at the central partthereof for opening the valve.

Numeral 106 designates a turnable valve lever mounted on a supportingplate 107 by a fulcrum 108 is provided with a left arm 109 positioned onthe left side thereof and close to the lower end of the diaphragm 105and, on the right side a projection 111 for closing a power supplyswitch 110 to supply power to the heater 78 when the valve is closed, anengaging surface 113 abutting on the lower end of a sliding rod 112, anda catching piece 117 so arranged as to hook the catching lever 116energized by a spring 115 through the lower part of a sliding plate 114and then locked.

The sliding plate 114 is configurated in such a shape to be verticallymovable by the turn of a link shaft 119 having a fulcrum 118 through theupper end thereof having a catching part 120, and, at ordinary times itis positioned low in engagement with a stopper 121 and positionallycontrolled low thereby. Numeral 122 designates an engaging lever havinga catching piece 124 energized by a spring 123 so as to engage with theupper end catching part 120 of the sliding plate 114 when this plate 114is raised.

The upper end of the sliding rod 112 is vertically movably arranged andsupported within a roughly cylindrical steam sensing tube 126protrusively disposed in parallel with the water tank 79 and fixed tothe supporting cover 125. Also, at the upper end of the sliding rod 112and between the inner surface of the steam sensing tube 126 and theflange 127 of the sliding rod, there is provided a coiled-spring-likesteam sensing element 128 made of a shape memory alloy such as Ti-Nialloy or Cu-Zn alloy and treated to elongate to the initial lengthmemorized at a predetermined temperature lower than 100° C. Numeral 129designates steam ports provided on the upper part of the steam sensingtube 126 for adapting the steam sensing element 128 to communicate withthe atmosphere and, against one of these ports, disposed is an openingat one end of the steam pipe 130 having the other end fixed to a pointabove the specified level of water in the water tank 79. Numeral 131 isa water-tight packing which vertically movably supports the lower partof the sliding rod 112 at the center thereof so that the steam sensingtube 126 communicating with the atmosphere may water-tightly beseparated from the interior of the vessel, the peripheral part thereofbeing fixed to the fixing plate 132 and the underside of the supportcover 125. Numerals 133 and 134 designate operation push-buttons whoseupper portions protrude from the upper operation part 135 of the supportcover 125, and one of them 133 a power switch button which is broughtinto contact with a catching piece 138 to catch a switch lever 137energized by a spring 136 and with a moving contact of the power switch139 and has a projection 140 which acts to close the power source lineswitch and is arranged to upwardly return to the initial position by theforce of a spring not shown. The other operation push-button 134 is aturn-off push-button arranged to normally upwardly return to the initialposition by a spring not shown, and, at the lower end thereof, there areprovided releasing pieces 141, 142 and 143 which are disposed near theswitch lever 137, catching lever 116, and engaging lever 122 and act torelease these levers from catching engagement in opposition to the forceof springs 136, 115 and 123 of these levers 137, 116 and 122,respectively. Numeral 144 is a peg frame for a magnet plug 145 providedon the side of the pillar 76 of the base 74.

Next, with reference to FIG. 7, an electric circuit will be elucidated.Numerals 146 and 147 designate power source terminals connected to thepower source of, for example, 100 V and correspond to both terminals inthe peg frame 144 shown in FIG. 4. At one end of the power sourceterminal 146, through a power switch 139 and to the other power sourceterminal 147 a series circuit of the cup warming heater 93 andtemperature control thermostat 99, and another series circuit of thepower supply switch 110, the heater 78, the safety thermostat (148 inthe drawing) for preventing burning of the empty water tank, and thetemperature fuse 149 (not shown) are parallelly connected across commonconnection points 150 and 151.

The action of the above-mentioned configuration will be described. Waterin the water tank 79 is heated by the heater 78 to be high intemperature and, when reaching the boiling point of 100° C., forcefullyspouts in the form of steam from the steam pipe 130 provided on the topof the water tank 79. Spouting steam instantaneously pours onto thesteam sensing element 128 made of the shape memory alloy through thesteam ports 129 of the steam sensing tube 126, when thecoiled-spring-like steam sensing element 128 subjected to severe changeof temperature from 30° C. or so as an ambient temperature to 100° C.quickly elongates to restore the initial shape thereof memorized at atemperature lower than 100° C., for example, 80° C. or so, due to astrong restitutive force.

The aforementioned movement depresses the sliding rod 112 through theflange 127, whereby the engaging surface 113 is depressed and operatesto turn the valve lever 106 clockwise. Thus, the power switch 110 isopened, and the circuit to the heater 78 is also opened to suspend powersupply, and heating of water in the water tank 79 is stopped. At thesame time, the lower end of the sliding plate 114 pushed by the catchinglever 116 energized by the spring 115 rides on the hook part of thecatching piece 117 turned as described above, but the catching lever 116can not engage with the catching piece 117 because of the sliding plate114 and can not control the movement of the valve lever 106 (Refer tothe part drawn with an alternate long and short dash line in FIG. 5).Elongation of the steam sensing element 128 keeps the valve lever 106depressed until when steam generated from water heated by the heater 78spouts out, the power supply switch 110 is opened by turning of thevalve lever 106 for suspending power supply to the heater 78 andspouting of steam, and restitutive force of the steam sensing element128 acting at a memorized temperature passes away with the fall of thetemperature of the element.

On the other hand, the turning movement of an arm 109 on the left sideof the valve lever 106 pushes upward and opens the valve 100 energizedby the spring 103 through the diaphragm 105. In this case, therestitutive force of the steam sensing element 128 made of the shapememory alloy that has been subjected to shape memory treatment is setstronger than the force of the valve spring 103 for opening the valve100. When the valve 100 is opened, boiling hot water in the water tank79 is poured onto coffee powder in the filter case 80 throughperforations of the diffuser 102 after passing through the hot watersupply port 97, valve case 99, and hot water supply pipe 101. A quantityof hot water poured at this time corresponds to that prepared for thefirst supply to be evenly poured onto coffee powder, enough for fullyswelling coffee powder, and effective for extraction of coffee essenceperformed by the second supply of hot water.

When the sliding rod 112 closes the hot water supply valve 100 by thevalve closing force thereof in association with the counterclockwiseturn of the valve lever 106 after the stop of steam spouting andconsequent extinction of restitutive force of the steam sensing element128, the sliding rod 112 is pushed upward and therefore the steamsensing element 128 restores the initial contracted state thereof. Atthis time, the lower end of the sliding plate 114 riding on the hookpart of the catching piece 117, due to counterclockwise turn of thevalve lever 106, raises the sliding plate 114, accompanied by the turnof the upper end of the link shaft 119. As a result, the upper catchingend 120 of the sliding plate 114 engages with the catching piece 124 ofthe lever 122 and the sliding plate 114 is caught to be high inposition.

Upon closing of the hot water supply valve 100, the supply of hot waterto coffee powder is stopped and also the power supply switch 110 isclosed by the projection 111 of the valve lever 106, whereby the heater78 is electrified and water in the water tank 79 is again heated. Not avery long time is needed to re-boil water which has been once boiled.

When steam again spouts from the steam pipe 130 to the steam sensingelement 128, the valve lever 106 again turns clockwise with the slidingrod 112 depressed by elongation of the steam sensing element 128. Then,the power supply switch 110 is opened and power supply to the heater 78is stopped, thereby heating of water in the water tank 79 being stopped.At the same time, the catching piece 117 is also depressed but thesliding plate 114 is kept high in position due to engagement thereofwith the catching lever 122, and the catching lever 116 easily catchesthe hook part of the catching piece 117 by the force of the spring 115.Such catching engagement is maintained preventing the counterclockwisereturn of the valve lever 106 even when steam stops spouting thereafter.

Then, the hot water supply valve 100 is opened by the arm 109 on theleft side of the valve lever 106 and hot water is again poured ontocoffee powder. The time to suspend the hot water supply after the firsthot water supply and before the second hot water supply is the so-called"steaming time", and is usually, 30 seconds or so.

Referring to FIG. 3, such states as above will further be described: Thesteam sensing element 128 elongates, opens the valve, and turns off thecurrent in the heater 78 (at the point A) at the temperature of steam of100° C.; steam generated by heating of water, however, continues tospout thereafter for a certain period of time (from point of time A tothat of a); after the cease of steam spouting, the steam sensing element128 loses restitutive force thereof by the force of closing the hotwater supply valve 100 and restores the initial contractedcoiled-spring-like shape while cooled (the time from a to B); during thetotal length of time (A to B), the valve is opened for the first supplyof hot water; then the valve is continuously closed for the time (B toC) until steam spouts due to re-heating and elongates the steam sensingelement 128; and, after the end (the point C) of steaming time duringwhich the valve is closed and hot water supply is suspended, the valveis continuously opened and turns off the current in the heater 78without operating in association with the movement of the steam sensingelement 128.

That is, by controlling the power supply switch 110 so as to makerepeated operation, the valve lever 106, sliding plate 114, catchinglever 116, link shaft 119, and sliding rod 112 can control the action ofthe hot water supply valve 110 so as to make automatic processing ofsuch steps of operation as the first supply of hot water→steaming→thesecond supply of hot water, by utilizing the shape memory effect of thesteam sensing element 128.

Since, in the first time supply of hot water, hot water has been evenlypoured onto the whole of coffee powder and coffee powder has been fullyswollen during the steaming time thereby providing such state thatcoffee essence is easily extracted, in hot water supplying of a secondand subsequent time, rich and flavorful tasty coffee essence iseffectively extracted and coffee liquid is filtered by the paper filter87, passed through the extraction port 85 on the bottom of the filtercase 80 and the liquid receiving port 90 of the cup lid, and becomescontained in the cup 88. Coffee liquid contained in the cup 88 is keptwarm at an appropriate degree of temperature by the cup warming heater93 and the temperature control thermostat 94.

With depressing of the turn-off push-button switch 134 after the use ofthe kettle, releasing pieces 141, 142 and 143 provided below thepush-button operate to release catching engagement of levers (switchlever 137, catching lever 116 and engaging lever 122) and the powerswitch 139 is opened whereas the power supply switch 110 is closed, andthe sliding plate 114 is moved downward with the movement of theengaging lever 122 and kept as it is, thereby the initial state in whichthe valve is closed as shown in FIG. 4 being restored. The heater 78 andthe cup warming heater 93 as circuitry are turned off and both operationpush-button switches 133 and 134 automatically upwardly return to theinitial positions while energized by the spring force. A length of timebetween pouring of hot water supplied from the water tank 79 onto coffeepowder and completing extraction of coffee essence for serving of coffeeliquid is set at 3 to 4 minutes according to the diameter of the hotwater supply pipe 101 and the length of displacement of the hot watersupply valve 100 at the time of opening.

Thus, a coffee kettle of this embodiment comprises a filter case 80 forcontaining coffee powder and a water tank 79 having a heater 78therewithin, a power supply and control unit (power supply switch 110,valve lever 106, sliding plate 114, catching lever 116, link shaft 119and sliding rod 112) for the heater 78, a steam sensing element 128 madeof the shape memory alloy operating upon sensing steam generated fromwater in the water tank 79, and a hot water supply valve 100 to supplywater in the water tank 79 to the filter case 80 in association with themovement of the steam sensing element 128; and the hot water supplyvalve 100 is of such structure that the supply of hot water is oncesuspended by the action of steam repeatedly spouted and is againperformed under control of the power supply and control unit of theheater 78; wherein a requirement as "To drip boiling water of hightemperature onto coffee powder in the first stage and, swelling coffeepowder to the full, complete extraction of coffee essence within 3 to 4minutes" is satisfied and a process "to steam the whole of coffee powderwith hot water of high temperature thereby enabling to provide a statein which coffee essence is readily extracted as a key to serving offlavorful and rich coffee liquid" is made possible, thereby taste ofserved coffee liquid being further improved.

Because of the use of boiling water for coffee extraction, even hardwater is softened and tasty water as a requirement for serving of tastycoffee liquid is available, thereby bad smell of chlorinated lime beingremoved so as not to degrade the taste of coffee liquid.

In addition, steaming effect is obtained through a structure utilizinggeneration of steam controlled by electrification of the power supplyswitch 110, and accordingly, a complicated mechanical timer requiringelectric wiring is not used, which leads to simpleness of structure,compactness, lightness in weight, and low cost in production thereof.

FIGS. 8 through 10 show still another embodiment of this invention inwhich a power supply and control unit is further improved, and, whileapplying the same reference numerals to the same parts as those in theprevious embodiments and omitting the description thereon, onlydifferent parts will be described as follows:

Numeral 152 indicates a changeover switch which is operable from outsideas the operator desires and provided with a movable contact 154positionally controllable in the vertical direction (upper position H,lower position L) in association with the movement of a changeover knob153 and another movable contact 156 moving downward in association withthe movement of a turning piece 155 disposed on the link shaft 119. Thischangeover switch 152 is, as shown in the circuit diagram in FIG. 9,connected to a diode 157 not shown in FIG. 8 and also to the heater 78in series.

Then, the action of the above will be elucidated.

When setting the changeover knob 15 in the upper position H, after thefirst supply of hot water, steam stops spouting and the valve lever 106turns counterclockwise to raise the sliding plate 114 and also turn thelink shaft 119, thereby closing the power supply switch 110 andelectrifying the heater 78, however, the movable contact 156 of thechangeover switch 152 is depressed by the turning piece 155 integralwith the link shaft 119 and, therefore, the changeover switch 152 andthe circuit of the diode 157 are connected in series with the heater 78.Accordingly, a heat quantity applied to water in the water tank 79 ishalved by the circuit of the diode 157 and the heating time (the time Tin FIG. 6) is prolonged. On the contrary, when the changeover knob 153is set in the lower position L, even when the movable contact 156 isdepressed by the turning piece 155, the changeover switch 152 is notclosed and heat quantity for heating water in the water tank 79 by theheater 78 is not halved in the same way as that in the previouslydescribed embodiment. That is, the apparatus is so configurated as topermit free change of steaming time which is the time for closing thevalve after the first supply of hot water and steaming effect can beutilized for a longer time when desired, thereby more enjoyment of richtaste of coffee being possible for the user. This means that thesteaming time is variable responding to the quantity of coffee to beserved and a combination of steaming effects is possible, for example, ashort steaming time for a small quantity of coffee and a long time forthe specified quantity or a long time for even a small quantity whereasa short time for the specified quantity.

Moreover, as shown in FIG. 10, by providing a changeover switch 158 inthe circuit including the heater 78 and connecting the normal-usecontact of this switch 158 to the heater 78 through a timer 159 havingthe time limiting element, the steaming time can be adjusted by steplessadjustment of starting time of electrification of the heater 78 and theabove-said steaming effect may be improved in wider range.

In this way, from this embodiment, the same effect as those of thepreviously described embodiments can be obtained and such an effect aspermitting the user to enjoy wide varieties of steaming effect byoperating the knob can be expected.

In the above-said embodiments, a number of levers are used as powersupply and control means; but, not being limited thereto, for example,such a structure that control of steam generation in the first stage ismade to be in association with electric circuit having a time-limitingelement or bimetal may be used.

The steaming time may be divided into several short ones during thesupply of hot water and varieties of the steaming effect can be widenedby varying the arrangement of the sliding plate 114 and employing anelement for repeat of the process of hot water supply-and-suspension inthe timer shown in FIG. 10.

Though the steam sensing elements 52 and 128 made of the shape memoryalloy were elucidated in the above-mentioned embodiments, other modesmay be adopted such that, for example, using thermistors or thermostatsinstead of this steam sensing elements, each of which are disposedopposite to the opening of the steam pipe 54 or 130, thereby to sensesteam spouting from the above-said opening and by configurating tooperate so as to open the hot water supply valve 38 or 100 by a drivingsource such as an electromagnetic valve and timer operatingsimulatneously and in association with the steam sensing element.

As apparent from the above description on the embodiments, a coffeekettle according to this invention comprises a filter case forcontaining coffee powder, a water tank provided with a heater, a powersupply switch for the above-mentioned heater, a steam sensing element tooperate upon sensing steam generated from water heated to boil in theabove-said water tank, and a hot water supply valve for supplying hotwater in the water tank to the filter case in association with the steamsensing element, and accordingly, since hot water to be supplied tocoffee powder is necessarily made boiling one and, a temperature of hotwater to be in contact with coffee powder is made high from thebeginning, coffee powder is swollen as fully as providing a statepermitting easy extraction of coffee essence extraction, and as aresult, the extraction operation is completed within 3 to 4 minutes,whereby a coffee essence is efficiently extracted satisfying arequirement as a key to extraction of coffee essence for serving tastyliquid, and genuinely flavorful and rich coffee liquid can be served.

Furthermore, since a temperature of hot water is sensed without fail asto whether boiling or not before poured onto coffee powder and, as aresult, free from fluctuation which may otherwise be caused according tothe number of servings, electric power consumption, and sensitivitychange in repeated use, hot water at the boiling point is stablysupplied any time and a high reliability in quality to serve tastycoffee liquid is always ensured.

Because of the application of boiling water to coffee essenceextraction, even hard water is softened to be tasty and bad smell ofchlorinated lime is removed so as not to affect the taste of coffee.

Further, since steam sensing is the performance of sensing quick changefrom the normal temperature of water to the boiling point thereof, itgives a tolerance in setting of a temperature and can eliminate sensingerror caused by the divergence, and therefore, high reliability anddecreasing of production cost becomes possible.

Further, this invention is excellent in respect of safety andoperability because automatic operation is possible with the knob aloneoperated and opening of the power supply switch can be performed inassociation with the movement of the steam sensing element.

We claim:
 1. A coffee kettle, comprising: a filter case for containingcoffee powder, a water tank having a heater, power supply and controlmeans for supplying electric power to said heater, a steam sensingelement communicated with said water tank and adapted to operate whilesensing steam generated when water in said water tank is heated toboiling, and a conduit for communicating said filter case with saidwater tank, said conduit having interposed therein a hot water supplyvalve for opening to supply hot water from the water tank to said filtercase in association with operation of said steam sensing element.
 2. Acoffee kettle as set forth in claim 1, wherein:said power supply andcontrol means for supplying electric power to said heater is arranged tointerrupt supplying electric power to said heater in association withoperation of said steam sensing element.
 3. A coffee kettle as set forthin claim 1, wherein:said power supply and control means for supplyingelectric power to said heater is adapted for, once in a coffeebeverage-making cycle, interrupting hot water supply to the filter casefor an interval of time, by controlling the hot water supply valve forproviding a pause between when coffee powder contained in said filtercase is dampened, and when a desired amount of coffee beverage is made.4. A coffee kettle as set forth in claim 3, wherein:said power supplyand control means for supplying electric power to said heater comprisesan operation part which is accessible from externally of said coffeekettle for variably setting the duration of said interval of time.
 5. Acoffee kettle as set forth in any one of claims 1 through 4,wherein:said steam sensing element includes a steam sensor made of ashape memory alloy.
 6. Appartus for brewing a hot coffee beverage,comprising:a filter support chamber adapted to support a supply ofinitially-dry ground coffee on a filter, to receive through an inletthereof located upstream of said supply of ground coffee heated waterfor infusing said supply of ground coffee, and to deliver through anoutlet thereof a hot coffee beverage; a water heating chamber served byan electrically-powered hot water heater, this chamber having an inletfor receiving water to be heated, and an outlet means operativelyconnected with said inlet of said filter support chamber for deliveringheated water from said water heating chamber to said filter supportchamber for infusing said supply of ground coffee; said water heatingchamber being adapted to receive a supply of water through said inletthereof for filling said water heating chamber to a level which providesa headspace within said water heating chamber; an openable/closablevalve incorporated in said outlet means of said water heating chamber; asteam sensor; inlet means communicating said steam sensor with saidheadspace of said water heating chamber; valve actuator meansoperatively communicating said steam sensor to said valve for openingsaid valve, at least for a limited time, when steam is sensed by saidsteam sensor via said inlet means.
 7. The apparatus of claim 6, furtherincluding:a heater switch for said electrically-powered hot waterheater; and means operatively at least indirectly connecting said heaterswitch with said steam sensor, so that electrical energy supply to saidhot water heater is reduced when said valve is temporarily opened afirst time and is raised when said valve is closed after having beentemporarily opened a first time; control means for said valve actuatormeans, this control means being arranged for:(a) temporarily openingsaid valve only briefly a first time when steam is sensed by said steamsensor via said inlet means, for delivering to said inlet of said filtersupport chamber enough nearly-boiling water to substantially fullydampen said supply of initially-dry ground coffee so that said supply ofground coffee swells, but little hot coffee beverage drains therefrom,whereupon said valve is temporarily closed; and (b) opening said valve asecond time when steam is again sensed by said steam sensor via saidinlet means, for delivering to said inlet of said filter support chamberenough nearly-boiling water to cause a substantial amount of hot coffeebeverage to drain from said dampened, swelled supply of ground coffee.